This invention relates generally to coherent jet technology.
A recent significant advancement in the field of gas lancing is the development of the coherent jet technology disclosed, for example, in U.S. Pat. No. 5,814,125xe2x80x94Anderson et al. In the practice of this technology, a high velocity gas jet ejected from a lance is maintained coherent over a relatively long distance by the use of a flame envelope around and coaxial with the high velocity gas jet. The flame envelope is generated by combusting respective streams of fuel and oxidant which are each annular to the ejected high velocity gas jet. The resulting coherent jet can be used to deliver gas into a liquid, such as molten metal, from a relatively long distance above the surface of the liquid. One very important application of this coherent jet technology has been for providing oxygen for use in an electric arc furnace.
It is desirable to employ coherent jet technology in other steelmaking operations such as basic oxygen furnaces. The potential for using coherent jet technology in a basic oxygen furnace and other large scale applications would be enhanced if the coherent jets were made longer.
Accordingly it is an object of this invention to provide a lance which may be used to provide a coherent gas jet which may be longer than comparable heretofore known coherent jets.
The above and other objects, which will become apparent to those skilled in the art upon a reading of this disclosure, are attained by the present invention which is:
A lance for providing at-least one coherent jet comprising:
(A) a main passageway communicating with at least one nozzle for providing main gas from the lance;
(B) a first annular passageway coaxial with and radially spaced from the main passageway for flow of cooling fluid;
(C) a second annular passageway coaxial with and radially spaced from the first annular passageway for flow of first flame envelope fluid;
(D) a third annular passageway coaxial with and radially spaced from the second annular passageway for flow of second flame envelope fluid;
(E) a fourth annular passageway coaxial with and radially spaced from the third annular passageway for flow of cooling fluid; and
(F) at least one flow passage for flow of cooling fluid between the first annular passageway and the fourth annular passageway.
As used herein the term xe2x80x9ccoherent jetxe2x80x9d means a gas jet which has a velocity profile for a considerable distance downstream of the nozzle from which it was ejected which is similar to the velocity profile which it has upon ejection from the nozzle.
As used herein the term xe2x80x9cannularxe2x80x9d means in the form of a ring.
As used herein the term xe2x80x9cflame envelopexe2x80x9d means an annular combusting stream coaxial with the main gas stream.
As used herein the term xe2x80x9clengthxe2x80x9d when referring to a coherent gas jet means the distance from the nozzle from which the gas is ejected to the intended impact point of the coherent gas jet or to where the gas jet ceases to be coherent.
As used herein the term xe2x80x9caxisxe2x80x9d means the imaginary line running longitudinally through the center of a lance.